A state fisheries crew will be working nights starting April 23 to gather brown trout population estimates on the Missouri River. Twice a year – spring and fall – members of the fisheries division of Fish, Wildlife and Parks electro-fish sections of the Missouri between Holter Dam and the town of Cascade. In the spring the work focuses on the river’s brown trout population, because many rainbow trout are in tributaries spawning. Come fall, brown trout spawn and it’s time to count the rainbows. This year’s spring survey work will cover two time periods: April 23-25 and May 7-8. The work takes place at night to better capture fish and to avoid disturbing anglers. Two boats will work the Craig and Cascade sections at the same time; both are equipped with lights and generators.